April 21, 1905.] 



SCIENCE. 



013 



as to the merits of Dr. Moore's suggested 

 method or as to its leaving the water abso- 

 lutely safe for potable purposes, but be- 

 cause, holding a political position, it was 

 well to fortify myself before attempting 

 anything unusual, I, therefore, communi- 

 cated with all the leading chemists of the 

 city, ^particularly the chemists in the health 

 department, and one other gentleman, 

 whose name I am not at liberty to mention, 

 but who is probably one of the three or 

 four greatest biological chemists in this 

 country, and had them all committed be- 

 forehand — not as agreeing that the ex- 

 periment would be a successful one in 

 eliminating the algge, but as emphatically 

 agreeing that if the method Dr. Moore had 

 suggested was adopted, there would be ab- 

 solutely no danger to any consumer in 

 drinking the water. 



So we proceeded to put the copper sul- 

 phate in the two large reservoirs, using 

 our own employees for the purpose. For 

 Lake Clifton 300 pounds of sulphate was 

 used, or about one part to 6,390,000 by 

 weight. The method of application was as 

 follows : The lake was first shut off entirely, 

 both at the inlet and outlet. The sulphate 

 was in four bags of 75 pounds each. One 

 bag at a time was suspended from the stern 

 of a rowboat, and as soon as it was about 

 three quarters dissolved another bag was 

 put out. The boat was rowed around the 

 lake in concentric courses about 40 or 50 

 feet apart, and at such a rate as to cover 

 the lake completely by the time the four 

 bags of sulphate were dissolved. It took 

 128 minutes to dissolve the 300 pounds 

 applied. A sample of the water was taken 

 near the center of the lake just previous to 

 the application of the sulphate and samples 

 were taken at the same place in the lake at 

 intervals of 24 hours after the application. 

 These samples were for biological analyses. 

 Samples of the lake water were also taken 

 in sterilized bottles, both before and after 



application of the sulphate, for bacteriolog- 

 ical analyses. 



The biological analyses indicate a very 

 great reduction in the number of algaj in 

 the first 48 hours after treatment, and prac- 

 tically a complete elimination of alga? in 

 120 hours. On account of rain falling in 

 the reservoir during treatment, unfortu- 

 nately the bacteriological analyses give no 

 correct indication of the action of the sul- 

 phate on the bacteria in the lake. These 

 analyses were all made by Dr. Wm. R. 

 Stokes, the city bacteriologist. An analysis 

 of the samples was also made by the city 

 chemist to determine the proportion of cop- 

 per present, and no trace of copper was 

 found in the water as early as 24 hours 

 after application of the sulphate. 



The method of treatment of Lake Monte- 

 bello was exactly the same as at Lake Clif- 

 ton, except that a larger amount of copper 

 sulphate was used ; 600 pounds were ap- 

 plied, or about one part in 6,685,800 by 

 weight. As with Lake Clifton, the analyses 

 showed a very considerable reduction in 

 the number of algas in 48 hours after appli- 

 cation of the sulphate, but the analyses of 

 samples taken at intervals of 24 hours 

 thereafter showed a slight increase in the 

 number of algte until the eighth day after 

 treatment, when the number per cubic cen- 

 timeter dropped to 14. At that time it was 

 found necessary to turn Lake Montebello 

 into consumption, and therefore no further 

 analyses were made. It is possible that if 

 the examination had been continued we 

 should have found the algae practically 

 eliminated, the same as at Lake Clifton. 



A chemical analysis showed no trace of 

 copper in the water five days after applica- 

 tion of the sulphate. 



We had no bacteriological analyses made 

 of the water in Lake Montebello because 

 our experience with Lake Clifton tended 

 to substantiate the intimation by Dr. Moore 

 that the proportion of copper sulphate 



